1. Field of the Invention
The present invention relates to an electronic musical instrument which is suitable for generating various kinds of sound.
2. Prior Art
conventionally, an electronic musical instrument which is based on FM (i.e. frequency modulation) sound technology contains a keyboard, a sound source block, an EG (i.e. envelope generator) block and a sound system, etc., in which a musical tone signal is generated by the sound source block corresponding to key-on operations, then affected by an envelope signal which generated by the EG block, where the envelope signal expansively varies when "segment" information changes. Then, the affected musical tone signal is generated by the sound system as a musical tone.
Further, electronic musical instruments containing microcomputers are recently popularized. However, when the whole electronic musical instrument is consisted with a microcomputer, the processing time of the microcomputer becomes extended, so that real-time musical operation becomes impeded. Consequently, the sound source block and/or the EG block of the conventional electronic musical instrument are constituted with hardware logic circuits. Such circuits have dedicated port registers corresponding to "A" (i.e. attack), "D" (i.e. decay), "S" (i.e. sustain) and "R" (i.e. release) segments (see FIG. 10) respectively, where the registers are controlled by commands from the microcomputer and control the EG block.
According to above-described technology, the conventional electronic musical instruments can carry out realtime music performance without burdening the microcomputer.
However, the prices of high performance and high speed microcomputers are reduced recently, so that such microcomputers are easy to be utilized to electronic musical instruments. By utilizing such high performance microcomputers in electronic musical instruments, satisfactory realtime music performance can be carried out because of their faster processing speed, so that it is needless to have dedicated port registers. Put another way, the conventional electronic musical instruments having dedicated port registers are unnecessarily expensive to manufacture.